An integrated testbed for advanced wireless networked control systems technology

Abstract

Wireless sensor networks (WSNs) have gained widespread acceptance during the last decade, largely due to the greatly increased flexibility, lower costs and scalability that they have been shown to provide. The pace of application in the context of wireless networked control systems (WNCSs) has been somewhat impeded, however, by the reluctance of industry to accept the risks of allowing wireless paths to be incorporated in process control loops. The problem is that there are conflicts between maintaining control loop performance, which can be degraded by many factors, such as low data rates, delays in wireless paths, jitter and electromagnetic interference; and the usual objectives in managing a wireless sensor network, namely freedom to configure the network and to adjust data rates at will, to maximize efficiency and to conserve energy consumption in battery-powered network nodes. In the context of developing advanced controls technology for systems with wireless networks in feedback paths there is a strong need for a test environment that can be used to explore all facets of such systems, including potential problems relating to control loop performance and WSN management. We propose to address this requirement by developing a new testbed for research in WNCSs by adding advanced control agents and process simulators from the Intelligent Control and Asset Management or ICAM project to an existing WSN testbed called the Wireless Industrial Sensor Network Testbed for Radio-Harsh Environments or WINTeR. This testbed has been custom developed for oil and gas industrial environments, i.e., it includes features such as electromagnetic interference and complex mul-tipath propagation. The proposed new testbed, hereafter called WINTeR-ICAM, will include the ICAM Supervisor, ICAM Agents and an additional agent to resolve conflicts between maintaining control loop performance and managing the WSN effectively and efficiently, called a WNCS Coordination Agent or WNCSCA. This agent is designed to be part of an intelligent supervisory control system, and to grant the WSN as much latitude in meeting its objectives as possible while maintaining the performance of control loops that incorporate wireless paths, thus adding to the safety and reliability of future WNCSs. Together, the process simulators, ICAM Agents and WINTeR will provide a powerful new environment for research and development of advanced WNCS technology, with WSN hardware and software in the loop; this novel conception is the contribution of this paper.